/*******************************************************************************
 * Copyright (c) 2006, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * Contributors:
 * IBM Corporation - initial API and implementation
 * Anton Leherbauer (Wind River Systems) - http://bugs.eclipse.org/247294
 ******************************************************************************/

package cn.elwy.rcp.ui.navigator;

import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.FileTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.ui.internal.navigator.Policy;
import org.eclipse.ui.navigator.CommonDragAdapterAssistant;
import org.eclipse.ui.navigator.INavigatorDnDService;
import org.eclipse.ui.part.ResourceTransfer;

/**
 * Clients may reference this class in the <b>dragAssistant</b> element of a <b>org.eclipse.ui.navigator.viewer</b>
 * extension point.
 * <p>
 * Clients may not extend or instantiate this class for any purpose other than
 * {@link INavigatorDnDService#bindDragAssistant(CommonDragAdapterAssistant)}. Clients may have no direct dependencies
 * on the contract of this class.
 * </p>
 * 
 * @since 3.2
 * @noextend This class is not intended to be subclassed by clients.
 */
@SuppressWarnings("restriction")
public class ResourceDragAdapterAssistant extends CommonDragAdapterAssistant {

  private static final Transfer[] SUPPORTED_TRANSFERS = new Transfer[] { ResourceTransfer.getInstance(),
      FileTransfer.getInstance() };

  private static final Class<IResource> IRESOURCE_TYPE = IResource.class;

  /*
   * (non-Javadoc)
   * @see org.eclipse.ui.navigator.CommonDragAdapterAssistant#getSupportedTransferTypes()
   */
  public Transfer[] getSupportedTransferTypes() {
    return SUPPORTED_TRANSFERS;
  }

  /*
   * (non-Javadoc)
   * @see org.eclipse.ui.navigator.CommonDragAdapterAssistant#setDragData(org.eclipse.swt.dnd.DragSourceEvent,
   * org.eclipse.jface.viewers.IStructuredSelection)
   */
  public boolean setDragData(DragSourceEvent anEvent, IStructuredSelection aSelection) {

    IResource[] resources = getSelectedResources(aSelection);
    if (resources.length > 0) {
      if (ResourceTransfer.getInstance().isSupportedType(anEvent.dataType)) {
        anEvent.data = resources;
        if (Policy.DEBUG_DND) {
          System.out.println("ResourceDragAdapterAssistant.dragSetData set ResourceTransfer"); //$NON-NLS-1$
        }
        return true;
      }

      if (FileTransfer.getInstance().isSupportedType(anEvent.dataType)) {
        // Get the path of each file and set as the drag data
        final int length = resources.length;
        int actualLength = 0;
        String[] fileNames = new String[length];
        for (int i = 0; i < length; i++) {
          IPath location = resources[i].getLocation();
          // location may be null. See bug 29491.
          if (location != null) {
            fileNames[actualLength++] = location.toOSString();
          }
        }
        if (actualLength > 0) {
          // was one or more of the locations null?
          if (actualLength < length) {
            String[] tempFileNames = fileNames;
            fileNames = new String[actualLength];
            for (int i = 0; i < actualLength; i++)
              fileNames[i] = tempFileNames[i];
          }
          anEvent.data = fileNames;

          if (Policy.DEBUG_DND)
            System.out.println("ResourceDragAdapterAssistant.dragSetData set FileTransfer"); //$NON-NLS-1$
          return true;
        }
      }
    }
    return false;

  }

  private IResource[] getSelectedResources(IStructuredSelection aSelection) {
    Set<IResource> resources = new LinkedHashSet<IResource>();
    IResource resource = null;
    for (Iterator<?> iter = aSelection.iterator(); iter.hasNext();) {
      Object selected = iter.next();
      resource = adaptToResource(selected);
      if (resource != null) {
        resources.add(resource);
      }
    }
    return (IResource[]) resources.toArray(new IResource[resources.size()]);
  }

  private IResource adaptToResource(Object selected) {
    IResource resource;
    if (selected instanceof IResource) {
      resource = (IResource) selected;
    } else if (selected instanceof IAdaptable) {
      resource = (IResource) ((IAdaptable) selected).getAdapter(IRESOURCE_TYPE);
    } else {
      resource = (IResource) Platform.getAdapterManager().getAdapter(selected, IRESOURCE_TYPE);
    }
    return resource;
  }

}
